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Baby Bottle on the end of the Static Tube

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Dean Westerburg

Active Member
Joined
Nov 2, 2020
Messages
29
I purchased a formerly flying Sonerai II L and the Static line from the altimeter and airspeed indicator run into a baby bottle in the back. Has anyone seen this before? What is the purpose?

PXL_20201206_205450334.jpg
 
My guess is the builder had trouble finding a location for the static source/port that was not "breezy" and thus affecting indications on the instruments. The lines into the bottle are probably to isolate the open ends into still air, and the bottle smooths out the pressure changes with changes in altitude. Back in the day it was common practice in gliders to put the static source for mechanical variometers in a thermos bottle loosely filled with brass scouring pads. That's not to say a static source inside the fuselage guarantees true static pressure. A friend had an airplane with an internal static source and when he opened the canopy vent the airspeed indicator dropped a bit.
 
Interesting. I figured there was some reason for it or why would it be there! Thanks for the reply. Maybe I will leave it in there for the first few flights and see how it goes.
 
Yep you can just slap a dry filter on the ASI and bam done. Best way is T to both sides of fuselage out of slip stream then test with alt air and slipstream flights. Find what’s best ie calibrated airspeed close to real AS.
 
Yep you can just slap a dry filter on the ASI and bam done. Best way is T to both sides of fuselage out of slip stream then test with alt air and slipstream flights. Find what’s best ie calibrated airspeed close to real AS.
What do you mean by a dry filter? I'm seriously considering using a desiccant pouch on the back of my altimeter. Sounds crazy but I think it'll work.
 
You can use anything even a dirty sock. Just make sure it’s serviceable unlike the ones on cessnas. I’d stay away from a desiccant. If your humid ever you’ll service it often and filters never have been a issue.
 
You can use anything even a dirty sock. Just make sure it’s serviceable unlike the ones on cessnas. I’d stay away from a desiccant. If your humid ever you’ll service it often and filters never have been a issue.
You the man. Saved me a 1/4" of clearance too lol. When I bought the plane the altimeter was fogged up. I brought the altimeter home and let it sit for a few days inside. The fog cleared up but I disconnected the whole static line and am rethinking it.
 
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